Calibration tool



FIG. 1 is a front, top and side perspective view of the calibration tool showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a front elevational view thereof; and,

FIG. 5 is a bottom elevational view thereof. 

The ornamental design for a calibration tool, as shown and described. 